Two-temperature refrigerating system



Dec. 18, 1956 J. H. HEIDORN 2,774,221

TWO-TEMPERATURE REFRIGERATING SYSTEM Filed July 14, 1953 INVENTOR. John H He/oom.

BY MW.

H/s Alia/ nay.

TWO-TEMPERATURE REFRIGERATING SYSTEM John H. Heidorn, Dayton, Ohio, assignor to General Motors Corporation, Detroit, Mich, a corporat on of Delaware Application July 14, 1953, Serial No. 367,867

6 Claims. (Cl. 62-4) This invention relates to refrigeratingapparatus and more particularly to an improved refrigerant circuit.

It is an object of this invention to provide a refrigerator having a pair of interconnected evaporators located respectively on relatively high and low temperature compartments and wherein the evaporator in the high temperature compartment may be efiectively defrosted without materially effecting the temperature in the low temperature compartment.

Another object of this invention is to provide an improved refrigerant circuit which shortens the effective length of the defrost cycle. More particularly it is an object of this invention to provide an evaporator accumulator between the low temperature evaporator and the high temperature evaporator which is designed to hold refrigerant during the off cycle and to make it immediately available to the system on the running cycle.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings, wherein a preferred form of the present invention is clearly shown.

In the drawings: a

Figure 1 of the drawing is a diagrammaticview showing the invention applied to a modern refrigerator; and,

Figure 2 is a fragmentary elevational view of the accumulator construction. a

Referring now to the drawing wherein a preferred embodiment of the invention has been shown, reference numeral 16 designates a conventional refrigerator cabi not having a frozen food storage compartment 12, an unfrozen food storage compartment 14, and a machinery compartment 16. The refrigerating systemconsists of the usual motor-compressor unit 20 which discharges compressed refrigerant into a condenser 22 wherein the refrigerant is converted from the vapor phase to the liquid phase before being supplied to the frozen food compartment evaporator 24. A capillary tube type of fixed restrictor 26 is provided as shownfor reducing the pressure of the refrigerant supplied to the evaporator24. The evaporator 24 is adapted to be operated at a low enough temperature to maintain the frozen foods stored in the compartment 12 at temperatures in the zero zone.

In the construction shown, the evaporator 24 comprises coils which are wrapped around the frozen food compartment liner 28 in accordance with well known practice. The amount of liquid refrigerant supplied to the evaporator 24 is such that some of the refrigerant will eventually overflow into a plate type evaporator 32 located in the compartment 14 so as to refrigerate the food stored in the compartment 14. A V-shaped accumulator 34 which is carried by the back wall of the liner 28 is interposed between the evaporators 24 and 32. The outlet from the evaporator 24 discharges into the lower end of the receiver 34 as indicated at 36. The sloping arms of the V-shaped accumulator assist in the process of disengaging the liquid on the accumulator from any vapor flowing upwardly through the liquid therein. The refrigerant line 33 which conveys liquid refrigerant from the tes Patent accumulator 34 to the evaporator 32 has its inlet 40 arranged adjacent the lower end of the accumulator 34 so that when the compressor withdraws refrigerant vapor from the evaporator section 32 liquid refrigerant will be withdrawn from the lower end of the accumulator 34. By virtue of this construction it is obvious that overflow refrigerant from the evaporator 24 'is fed into the accumulator 34 and that this excess refrigerant is readily available for feeding into the evaporator 32 in response to suction produced by the operation of the compressor. The motor-compressor unit 20 is controlled by means of a thermostatic-bulb 42 which operates a switch 44 in the compressor control circuit as shown. This switch is of the type which is designed to be closed whenever the temperature of theevaporator 32 goes above 34 F and to reclose at a predetermined value such as 2 -F. Once the switch closes so as to start the motor-compressor unit, it'will remain closed until the temperature of the evaporator 32 is reduced to the-2 F. settingof the the 34 F. value.

During the off cycle the compressor does notwithdraw any refrigerant vapor from the evaporator 32 and the liquid refrigerant which is in the evaporator 32 tends to return to the accumulator 34 either in the form of liquid refrigerant or vapor. The reason that liquid refrigerant in the evaporator 32 returns to the evaporator 24 is that the evaporator 32 is provided with accumulator chambers 46 and 48 which are so arranged that the gas pressure within the chambers 46 and 48 resulting from vaporization of refrigerant in the evaporator 32 during the off cycle tends to force some refrigerant still in the liquid phase to return to the accumulator 34. V

A small hole 50 has been provided in the line 38 -adjacent the upper end of the accumulator 34 so that vaporized refrigerant: from the evaporator section 32 is free to return to the upper end of the aecumulator34 so as'to be re'condensed when 'coming' in contactwith the colder-temperatures prevailing therein. The size of ,the hole SO-is large enough to handle the return fiow of it. has been found thatthehole 50 can be 51 diameter hole-located approximately 1" inside the accumulator. By vlr tue of the above described accumulator arrange ment it is. possible to use a larger charge of liquid "refrigerant in the systern without unwanted spillover into the'high temperature evaporator during the oif cycle. and yet make this liquid refrigerant available fonusein the high temperature evaporator at the very beginning of the on cycle.

It has been found that the application of heat to the 1 evaporator 32 during the defrost cycle facilitates both the return of liquid refrigerant from the evaporator 32 to the accumulator 34 and the melting of the ice and thereby shortens the length of the off cycle. It has also been found .that a secondary refrigerating system, which includes an evaporator portion 60 arranged in thermal exchange relationship with the walls of the food compartment 14 and a secondarycondenser portion 62 a arranged in thermal exchange relationship with that portion of the evaporator 32 serves the dual purposes of adding heat to the evaporator 32 during the defrost cycle and effectively refrigerates the outer walls of the food compartment 14. v

While the form of embodiment of the invention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted, as may come within the scope of the claims which follow.

What is claimed is as follows:

1. In a refrigerating system, a cabinet having a plurality of compartments therein, a compressor, a condenser, a first evaporator section in one of said compartments, a second evaporator section in another of said compartments, means for connecting said compressor, condenser and said first and second evaporator sections in series refrigerant flow relationship, said last named means including an accumulator located between, said evaporator sections, said accumulator including means forming a relatively large chamber having an inlet through which liquid refrigerant from said first evaporator section feeds and an outlet pipe extending down into the lower portion of said chamber through which refrigerant is fed to saidsecond evaporator section, said outlet pipe having a small vent hole located in said chamber adjacent, the upper end of said chamber. t

2 In a refrigerating system, a cabinet having a plurality of compartments therein, a compressor, a condenser, a first evaporator section in one of said compartments, a second evaporator section in another 'of said compartments, means for connecting said compressor, condenser and said first and second evaporator sections in series refrigerant flow relationship, said last named means including an accumulator located between said evaporator sections, said accumulator including means .forming a relatively large chamber having an inlet through which liquid refrigerant from said first evaporator section feeds and an outlet pipe extending down into the lower portion of said chamber through which refrigerant is fed to said second evaporator section, said outlet pipe having a small vent hole located in said chamber adjacent the upper end of said chamber, said chamber having a sloping portion intermediate said inlet and its upper end.

3. In a refrigerating system, a cabinet having a plurality of compartments therein, a compressor, a condenser, a first evaporator section in one of said compartments, a second evaporator section in another of said compartments, means for connecting said compressor, condenser and said first and second evaporator sections in series refrigerant flow relationship, said last named means including an accumulator located between: said evaporator sections, said accumulator including means formingv a relatively large'chamber into which liquid refrigerant from said first evaporator section feeds and an outlet pipe extending down into the lower portionsof said chamber through which refrigerant is fed to said second evaporator section, said outlet pipe having a small vent hole located above the normal liquid level in said chamber, and means responsive to temperature changes of said second evaporator section for starting and stopping said compressor. 7 t

4. In a refrigerating system, a cabinet having a plurality of compartments therein, a compressor, a condenser, a first evaporator section in one of said compartments,

a second evaporator section in another of said compartments, means for connecting said compressor, condenser and said first and second evaporator sections in series refrigerant flow relationship, said last named means including an accumulator located between said evaporator sections, said accumulator including means forming a relatively large chamber into which liquid refrigerant from said first evaporator section feeds and an overflow pipe extending down into said chamber through which refrigerant is fed to said second evaporator section, means for starting and stopping said compressor, and means for applying heat to said second evaporator section while said compressor is stopped.

5. In a refrigerator, a cabinet having relatively high and low temperature compartments, a compressor, a condenser, a first evaporator section in said low temperature compartment, a second evaporator section in said high temperature compartment, means for connecting said compressor, condenser and said first and second evaporator sections in series refrigerant flow relationship, said last named means including an accumulator located between said evaporator sections, said accumulator including means forming a relatively large chamber into which liquid refrigerant from said first evaporator section feeds and an overflow pipe extending down into said chamber through which refrigerant is fed to said second evaporator section, said overflow pipe having a small vent hole located above the normal liquid level in said chamber, means for applying heat to said second evaporator section, said last named means comprising a secondary refrigerant system having an evaporator section in thermal exchange relationship with the walls of said high temperature compartment and having a condenser portion arranged in thermal exchange relationship with said second evaporator section.

6. In a refrigerating system having a pair of evaporators connected in series wherein the last of said evaporators is adapted to be defrosted cyclically, means forming a pair of insulated compartments for separately enclosing said evaporators, an accumulator for momentarily storing overflow refrigerant from said first evaporator section before being supplied to said second evaporator section, said accumulator comprising an outer receptacle having an inlet connected to said first evaporator section, an outlet tube for conveying liquid refrigerant from said accumulator to said second evaporator section, said outlet tube being arranged to enter the upper end of said receptacle andvex'tending downwardly into the lower end thereof and having a vent hole provided in its wall adjacent the upper end of said receptacle.

References Cited in the file of this patent I UNITED STATES PATENTS 2,291,362 Warneke July 28, 1942 2,291,363 ,Atchison July 28, 1942 2,292,405 Reeves Aug. 11, 1942 2,622,405 7 Grimshaw Dec. 23, 1952 2,640,327 Alsing June 2, 1953 

